It could be done, for sure. But I'm afraid that political correctness might infiltrate it more easily than in the case of Narnian films. A screenwriter might, for example, take the man enslaved by the lizard of lust, and change his sin into not being sensitive and feminist enough.
But if it can be done and NOT be ruined, I'd like to see Ian Holm be rewarded for all the good performances he's given us over the years by his being cast as George MacDonald.